Young babies should always be placed on their back to sleep. From the perspective of prevention of SIDS (Sudden Infant Death Syndrome), placing a baby on his back to sleep, with feet near the bottom of the crib is absolutely the safest position. Some babies with reflux or colic seem to prefer to be slightly elevated, and a maximum 30-degree tilt at the top end of the cot or mattress may be suggested. Check with your paediatrician about sleep positions if your baby has reflux or other medical issues.
Once your baby is able to roll completely (at four to five months on average) and is doing so easily and on a regular basis – that is, front to back, and back to front; and rolls over in his cot and during activity time confidently and happily, with no difficulty getting back onto his back, then make sure he is no longer swaddled for sleep but is in either a sleep sack/grobag or sleep suit for freedom of movement.
At this point if he prefers to sleep on his tummy you will probably find that when you put him into the cot on his back, he will generally keep rolling onto his front. This is perfectly fine as long as your baby is:
- Capable of returning to his back without difficulty
- The room temperature is not too warm
- There is nothing obstructive in his cot, such as blankets, bumpers, big soft toys, pillows or bolsters etc.
You can reposition your baby onto his back but you will often find that he is on his tummy again the next time you check!